First of all because they have elevated their beliefs to a religion. Secondly, they believe that all behaviors should lead to equal outcomes, so when they don't they must blame someone or something for the failure. Case in point, we all know why Hillary lost, she lost because she is a lousy candidate and more Americans rejected the social policies of the Democrats than Americans who accepted their progressive social policies. In short, they are behaving like religious fanatics whose religion is being attacked by a rival religion.